1. Field of the Invention
The present invention is directed to an optical adaptor that permits the conversion of objective lenses designed for a certain image format to be utilized on optical devices having a smaller effective image format, more particularly the optical adaptor permits the use of exchangeable objective lens of a 35 mm single lens reflex camera on a T.V. camera and/or a motion picture camera.
2. Description of the Prior Art
Various forms of optical adaptors and converters are broadly known in the prior art for example, as disclosed in the Japanese Utility Model Publication No. 52,1130 and Japanese Patent Publication No. 51-151537. These devices have permitted objective lens to be attached to an optical device having a different mount and also to adjust the axial air space between the optical device and the objective lens.
Generally, the transmitted image will have a limited field of view as compared to the original capacity of the objective lens when used in the mode where it was originally intended to be utilized. Thus, frequently an objective lens system would be converted into a telephoto lens when used with an adaptor for an optical device having a smaller image format.
Particularly in the movie and video field, prior art limitations have restrained the use of objective lens systems, such as have been developed for 35 mm single lens reflex cameras, to be converted for use with either a T.V. or movie camera.
Of general interest is a binocular adaptor that has been designed for connecting a camera, having a recess lens, with a binocular device as shown in U.S. Pat. No. 3,981,021. In this regard, a lens system is provided in the adaptor housing having a negative refractive power to permit connection with a small pocket camera.
Finally, it has been known in the prior art to utilize rear converters to convert the focal distance of an objective lens system to a desired distance. These conventional rear converters, however, do not permit the utilization of an objective lens of a given image format size for utilization on a smaller image format optical device. These rear converters are intended for use on objective lenses and optical devices having identical image formats.
Accordingly, the prior art in the movie and video industry has not realized the full potential of using 35 mm objective lenses on movie and video cameras.